JP3479557B2 - Method for producing titanium-containing steel - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a titanium-containing steel having excellent titanium yield and titanium concentration adjustment accuracy.

[0002]

2. Description of the Related Art Titanium-containing steel is widely used in ordinary steel and stainless steel due to its excellent characteristics. As titanium-containing stainless steel, SUS430
LX, SUS436L, SUS444, SUH409 and SUS321 are generally known. In the stainless steel, titanium is added to the steel in order to enhance workability and weldability and to stabilize carbides and enhance intergranular corrosion resistance. Among these titanium-containing stainless steels, SUH409 (11% Cr-Ti steel) is the most widely used because it is inexpensive and has excellent workability.

Generally, stainless steel is coarsely smelted in a primary smelting furnace such as an electric furnace or a converter, and then subjected to the AOD method (Argon Oxygen).
Decarburization) and VOD method (Vacuum OxygenDecarbu
The so-called secondary refining, such as decarburization of molten steel, degassing, stirring and component adjustment, is carried out. A
The OD method is a refining method in which a mixed gas of argon and oxygen is blown into the molten steel from the bottom of the AOD furnace to suppress deoxidation of chromium and decarburization. The VOD method is a refining method in which a vacuum ladle degassing device is equipped with an oxygen sparging device, and molten steel in the ladle is decarburized while suppressing oxidation of chromium by top blowing oxygen and argon stirring from the bottom in a depressurized state. Is.

FIG. 7 is a schematic view showing a simplified structure of a vacuum ladle degassing apparatus which can suitably carry out the VOD method. The production of titanium-containing stainless steel is performed as follows. Molten steel that is roughly refined in the converter is poured into and held in the ladle 21. The ladle 21 which has received the molten steel is housed in the vessel 22. A vessel cover 23 is airtightly mounted on the vessel 22, and the internal space is sucked and decompressed by a vacuum pump. Argon gas is blown into the molten steel from a porous plug 24 provided at the bottom of the ladle 21 to stir the molten steel. Oxygen gas is in the vessel cover 2
3 is sprayed onto the surface of the molten steel from a lance 25 mounted so as to be able to move up and down. Molten steel is decarburized and refined by oxygen sparging under reduced pressure stirring.

After the decarburization refining is completed, aluminum is deoxidized by introducing aluminum while continuing decompression and stirring of argon gas. Aluminum deoxidation is performed for about 1.5 minutes. After that, titanium is added and the primary adjustment of the components is performed. Titanium is an element that has a strong affinity for oxygen, and when added to molten steel, it is oxidized by oxygen in the steel and easily reduced oxides in slag. The reason why titanium is added after deoxidizing aluminum is to suppress the oxidation of titanium. After the primary adjustment, the vacuum is released and the temperature measurement sampling and component analysis of the molten steel are performed. From the component analysis value after the primary adjustment, the yield of titanium input as the primary adjustment is calculated as the primary titanium yield.

FIG. 8 shows the relationship between the aluminum concentration of molten steel and the primary titanium yield in the prior art. The type of molten steel is 11% Cr-0.2% Ti steel. It can be seen from FIG. 8 that the primary titanium yield improves as the aluminum concentration of the molten steel increases. The higher the aluminum concentration of the molten steel, the more sufficient the deoxidation of the molten steel and the reduction of the slag are performed, so that the yield of titanium increases. However, the amount of oxygen in steel and the amount of easily reduced oxide in slag are not constant, and the aluminum concentration after deoxidation varies due to various fluctuation factors. Since the fluctuation of the aluminum concentration causes the fluctuation of the primary titanium yield, the titanium concentration after the primary adjustment becomes unstable. When the titanium concentration after the primary adjustment falls below the target titanium concentration, titanium is additionally added to the molten steel as the secondary adjustment. Secondary adjustment is done in the atmosphere. Generally, the higher the primary titanium yield, the higher the titanium yield in the secondary adjustment, so the amount of additional titanium to be added for secondary adjustment is determined by an empirical method considering the primary titanium yield. Has been done.

[0007]

According to the prior art, in the production of titanium-containing steel, the aluminum concentration of the molten steel after aluminum deoxidation varies due to various factors. Factors that change the aluminum concentration include the type of molten steel,
Weight, temperature, type of container such as furnace and ladle, capacity, stirring force of molten steel, degree of vacuum in vessel, oxygen concentration of molten steel,
The amount of slag, composition, basicity, raw material components such as titanium and aluminum, shape, particle size, particle weight, aluminum deoxidation time, etc. Fluctuations in aluminum concentration result in fluctuations in primary titanium yield. As described above, the higher the aluminum concentration, the higher the primary titanium yield.
The higher the primary titanium yield, the higher the titanium yield in the secondary adjustment, and thus the total titanium yield, which is the yield of titanium input as the primary adjustment and the secondary adjustment, increases. However, conversely, if the primary titanium yield decreases, the total titanium yield decreases. Therefore, it is necessary to elucidate the influence of each of the above factors and to stabilize the aluminum concentration at a high level and improve the primary titanium yield.

Further, according to the prior art, since the amount of additional titanium to be added for the secondary adjustment is determined by an empirical method, the titanium concentration adjustment accuracy after the secondary adjustment is not sufficient. There is. When the titanium concentration after the second adjustment is lower than the target component range, readjustment is required, resulting in a decrease in efficiency and productivity. When the titanium concentration after the secondary adjustment is higher than the target composition range, the amount of inclusions such as TiO ₂ and TiN in the molten steel increases, and if these are taken into the steel during solidification, streak defects occur in cold rolling. As a result, the surface quality of the product deteriorates. Therefore, it is necessary to establish a logical second-order adjustment method of titanium concentration rather than an empirical method to improve the titanium concentration adjustment accuracy.

An object of the present invention is to provide a method for producing titanium-containing steel which is excellent in titanium yield and titanium concentration adjustment accuracy.

[0010]

The present invention is a method for producing a titanium-containing steel in which aluminum and titanium are put into molten steel containing chromium, while an inert gas such as argon is blown from the bottom of the container while stirring. Blow a fixed amount of oxygen to decarburize while preventing oxidization of chromium, and then blow aluminum while continuing stirring after stopping the oxygen blowing, and set the stirring power to ε and the molten steel volume to V1. when, after the deoxidation and held by equation log (tm) = 2.5-0.45log (εV1 -2/3) 12 times or less of the time more than 7 times the uniform mixing time tm satisfying, A method for producing a titanium-containing steel, which is characterized in that titanium is added.

Further, the present invention is characterized in that the holding time while stirring is 5 minutes or more and 10 minutes or less.

The present invention also provides a method for producing a titanium-containing steel in which aluminum and titanium are charged into molten steel, in which aluminum is charged and an inert gas such as argon is blown from the bottom of the container and stirred for a predetermined time. After carrying out deoxidation by holding it for the first time, the primary adjustment of the components is performed by adding titanium, the yield of the added titanium is determined as the primary titanium yield, and titanium is added to the molten steel as the secondary adjustment. The total titanium yield, which is the yield of titanium to be added as the primary adjustment and the secondary adjustment when additionally feeding, uses the preset functions of the primary titanium yield and the total titanium yield. Of the titanium-containing steel, characterized in that the amount of titanium for secondary adjustment required to obtain the target concentration of titanium is determined based on the predicted total titanium yield. It is a manufacturing method.

The present invention is also characterized in that the functions of the primary titanium yield and the total titanium yield are obtained based on the moving average value of the immediately preceding operation.

[0014]

According to the present invention, the titanium-containing steel containing chromium is blown with an inert gas into the molten steel from the bottom of the container and stirred, and oxygen is blown to decarburize while preventing oxidation of chromium. After aluminum is added to deoxidize, titanium is added to perform ingot production. Deoxidation of aluminum is carried out for a period of 7 times or more and 12 times or less of the uniform mixing time. The uniform mixing time is determined by an equation using the stirring power and the volume of molten steel. As described above, since titanium is added after the deoxidation of molten steel and the reduction of slag by aluminum, the oxidation of titanium is suppressed and the yield of titanium is improved.

Further, according to the present invention, aluminum deoxidation is performed for 5 to 10 minutes. Since the aluminum deoxidizing time is longer than the aluminum deoxidizing time of the prior art of about 1.5 minutes, deoxidation of molten steel and reduction of slag are sufficiently performed.

Further, according to the invention, titanium is introduced after aluminum deoxidation as a primary adjustment of components while blowing an inert gas or the like from the bottom of the container and stirring, and the yield of the introduced titanium is first After obtaining the next titanium yield,
Titanium is additionally added as the second adjustment. The total titanium yield, which is the yield of titanium to be input as the primary adjustment and the secondary adjustment, was predicted using a function of the preset primary titanium yield and total titanium yield, and was predicted. The input amount of titanium for secondary adjustment is determined based on the total titanium yield. In this way, the amount of titanium for secondary adjustment is determined through a logical procedure, so that the accuracy of titanium concentration adjustment is greatly improved.

Further, according to the present invention, since the functions of the primary titanium yield and the total titanium yield are obtained on the basis of the moving average value of the immediately preceding operation, the total titanium is maintained even if the operating conditions change. The yield prediction accuracy can be maintained at high accuracy.

[0018]

EXAMPLES A method for producing titanium-containing stainless steel according to an example of the present invention will be described with reference to FIGS. 1 to 6. FIG. 1 is a cross-sectional view showing a simplified structure of a vacuum ladle degassing apparatus capable of suitably carrying out the method of the present invention, and FIG. 2 is a melting chart of titanium-containing stainless steel according to an embodiment of the present invention. It is explanatory drawing which shows the manufacturing process, FIG. 3 is a figure which shows the relationship between the aluminum deoxidation time represented by the multiple of the uniform mixing time, and the primary titanium yield, and FIG. 4 is aluminum of the molten steel in the method of this invention. FIG. 6 is a diagram showing the relationship between the concentration and the primary titanium yield, and FIG. 5 is a scatter diagram showing the relationship between the total titanium yield of 11% Cr-0.2% Ti steel and the primary titanium yield. FIG. 6 is a diagram showing the deviation between the analysis value of the final titanium concentration and the target value when the component adjustment is performed by applying the method of the present invention.

As shown in FIG. 1, an 80T vacuum ladle degassing apparatus 1 comprises a vessel 2 and a vessel cover 3 mounted on the vessel 2. The side wall of the vessel 2 is provided with a suction tube 5 connected to the vacuum exhaust means 4. The vessel cover 3 is provided with an oxygen-sparing lance 6 that is vertically and airtightly mounted, a temperature measurement sampling device 7, and a plurality of alloy addition devices 8. Titanium-containing stainless steel, for example, 11% Cr-0.2% Ti steel is melted in the following manner. Molten steel 9 that is roughly refined in a converter is poured into and held in a ladle 10. The ladle 10 that has received the molten steel 9 is housed in the vessel 2. Vessel 2
An inner space 1 on which a vessel cover 3 is airtightly mounted and which is closed by the vessel 2 and the vessel cover 3
3 is sucked and decompressed by the vacuum evacuation means 4. A plurality of inactive gas, eg, argon gas, is provided at the bottom of the ladle 10 via the supply pipe 11 to form a porous plug 12.
The molten steel 9 is agitated by being blown into the molten steel 9. The porous plug 12 is made of a porous refractory material.

As shown in FIG. 2, oxygen sparging is performed in the first stage of the melting process. Oxygen blowing is performed to decarburize molten steel. Oxygen gas is blown onto the surface of the molten steel 9 from the oxygen spraying lance 6. The molten steel 9 is decarburized and refined by degassing with oxygen and stirring with argon gas. The oxygen ejaculation is stopped after the ejaculation of a predetermined amount. Even after stopping the oxygen blowing, the depressurized state is maintained and the argon gas stirring is continued until the carbon concentration in the molten steel reaches the target concentration to accelerate the decarburization reaction.

In the second stage, aluminum is introduced through the alloy addition device 8 to deoxidize the molten steel. The aluminum charged is, for example, in the form of small pieces, and its purity is 97%. The introduction of aluminum is performed while stirring the molten steel 9 under a reduced pressure with argon gas. The degree of vacuum at the time of introducing aluminum is about 20 Torr. The deoxidation of aluminum is carried out for a time of 7 times or more and 12 times or less of the uniform mixing time tm of molten steel. Stirring with argon gas under reduced pressure is continued during deoxidation of aluminum to promote deoxidation reaction of molten steel and reduction reaction of slag. The uniform mixing time tm (s) of the molten steel is ε for the stirring power and Vl (m ³ ) for the volume of the molten steel.
Is defined by the following equation (1).

[0022] log (tm) = 2.5-0.45log (εVl -2/3) ... (1) stirring power ε has a gas flow Vg (Nm ³ / min), the molten steel temperature Tl (K), When the mass of molten steel is Ml (T), the gas blowing depth is h (m), the atmospheric pressure is P (Pa), the constant is η, and the gas temperature at the time of blowing is Tg (K),
For example, it can be obtained from the following formula (2) described on page 48 of "Metal Handbook", revised 5th edition, published by Maruzen Co., Ltd. March 31, 1990.

[0023]

[Equation 1]

Therefore, the uniform mixing time tm of the molten steel is
It can be obtained from the equation (1) using the stirring power ε obtained from the equation (2) and the volume Vl of the molten steel. For example, under typical operating conditions, gas flow rate Vg = 0.6 Nm ³ / m
in, molten steel temperature Tl = 1900K, molten steel mass Ml = 78
T, gas injection depth h = 2.2 m, atmospheric pressure P = 2
700 Pa, constant η = 0.06, gas temperature during blowing Tg = 300 K, and volume of molten steel 11 m ³ ,
From equations (1) and (2), the uniform mixing time tm of molten steel is 46 seconds.

After the aluminum deoxidation is carried out for a predetermined time, for example 6 minutes, titanium is introduced into the molten steel in the third stage as the primary adjustment of the components. The titanium to be charged is small sponge titanium. Titanium is charged under reduced pressure while stirring the molten steel 9 with argon gas.
Following the third step, the vacuum is released in the fourth step, and the temperature measurement sampling device 7 is used to perform temperature measurement and sampling at the same time. Further, thereafter, the component analysis of the collected sample is performed. The vacuum release is performed approximately 2 minutes after the titanium is charged. After the component analysis, in the fifth step, the yield of titanium input in the primary adjustment is calculated from the titanium analysis value as the primary titanium yield.

FIG. 3 shows the relationship between the aluminum deoxidation time expressed as a multiple of the uniform mixing time and the primary titanium yield. In FIG. 3, the aluminum concentration of the molten steel is 0.10.
The range is 0.12%. The operating conditions are the same as the typical operating conditions described above. From FIG. 3, it can be seen that as the aluminum deoxidation time increases, the primary titanium yield improves. Further, the primary titanium yield increases sharply as the aluminum deoxidizing time increases up to 7 times the uniform mixing time tm, but the primary titanium yield exceeds 7 times the uniform mixing time. It can be seen that almost no improvement in the stay is observed. The reason for limiting the aluminum deoxidation time to 7 times or more of the uniform mixing time tm of molten steel is for the above reason. Further, the aluminum deoxidation time is limited to 12 times or less of the uniform mixing time tm of the molten steel, not only the improvement of the primary titanium yield is not observed even if the time is further increased, but also the longer the molten steel temperature is This is because the harmful effects such as a decrease in productivity and a decrease in productivity increase.

As the aluminum deoxidation time increases, the deoxidation of molten steel and the reduction of slag sufficiently proceed, so that the oxidation of titanium is suppressed and the primary titanium yield is improved. However, since the amount of effective aluminum gradually decreases with the oxidation of aluminum, the effect of improving the primary titanium yield gradually becomes saturated. Further, since the deoxidizing time of aluminum is determined based on the versatile uniform mixing time, the method of the present invention is not limited to specific equipment and specific operating conditions, but also to various equipment and various operating conditions. Can be applied. In the case of the typical operating conditions, the uniform mixing time of molten steel is 46 seconds, so the aluminum deoxidizing time is 5 to 10 minutes. The aluminum deoxidizing time is longer than the aluminum deoxidizing time of the above-mentioned conventional technique of about 1.5 minutes. Therefore, since deoxidation of molten steel and reduction of slag sufficiently proceed, oxidation of titanium is suppressed and primary titanium yield is improved.

FIG. 4 shows the relationship between the aluminum concentration of molten steel and the primary titanium yield in the method of the present invention. In order to facilitate comparison, FIG. 4 also shows the relationship between the aluminum concentration of molten steel of the same steel type and the primary titanium yield in the prior art shown in FIG. The aluminum deoxidizing time of molten steel is 5 to 10 minutes in the method L1 of the present invention and 1.5 minutes in the conventional method L5. From FIG. 4, (a) Inventive method L
1. As for the conventional method L5, the higher the aluminum concentration in the molten steel, the higher the primary titanium yield. (B) The primary titanium yield of the method L1 of the present invention is better than that of the conventional method L5 regardless of the aluminum concentration of the molten steel. (C) It can be seen that the standard deviation of the primary titanium yield is smaller in the method L1 of the present invention than in the conventional method L5. The higher the aluminum concentration of the molten steel, the more sufficiently the deoxidation of the molten steel and the reduction of the slag are performed, so that the oxidation of titanium is suppressed and the primary titanium yield increases. However, if the aluminum concentration becomes high, the weldability after commercialization deteriorates, so the aluminum concentration in the molten steel cannot be increased without limit. The aluminum concentration of the molten steel is selected in the range of 0.02 to 0.20%. Further, as the aluminum deoxidation time becomes longer, the deoxidation of molten steel and the reduction of slag sufficiently proceed to reduce the undeoxidized and unreduced regions, so that the oxidation of titanium is suppressed more than when the aluminum deoxidation time is short. It Therefore, the longer the aluminum deoxidation time, the higher the primary titanium yield regardless of the aluminum concentration in the molten steel,
And the standard deviation becomes smaller.

When the titanium concentration after the primary adjustment falls below the target titanium concentration, the amount of titanium additionally fed in as the secondary adjustment is calculated in the sixth step. The amount of titanium added additionally is calculated by predicting the total titanium yield, which is the yield of titanium input as the primary adjustment and the secondary adjustment. The total titanium yield is predicted using a preset function of the primary titanium yield and the total titanium yield. The function is obtained by expressing the relationship between the total titanium yield of 3 charges or more and 20 charges or less immediately before and the primary titanium yield of the same steel type melted in the past by a regression equation. 11% Cr-
Fig. 5 shows the relationship between the total titanium yield and the primary titanium yield investigated for the 20 charges just before 0.2% Ti steel.
Shown in. It can be seen from FIG. 5 that there is a good linear correlation between the two, so that the total titanium yield can be mathematically expressed as a linear function of the primary titanium yield. The correlation coefficient between the two in FIG. 5 is 0.98, which is very high. It can be seen from FIG. 5 that the total titanium yield can be predicted with high accuracy from the primary titanium yield.

WT2 (kg) is the amount of titanium added additionally, WT1 (kg) is the amount of titanium added during the primary adjustment, Ti2 (%) is the total titanium yield, and WM (kg) is the weight of molten steel. The subsequent titanium concentration is [Ti] (%), the primary titanium yield is Ti1 (%), and the final target titanium concentration is 0.2%.
Then, [Ti] × WM = WT1 × Ti1 (3) (WT1 + WT2) × Ti2 = 0.2WM (4) From formula (3) and formula (4), the amount of titanium added WT
2 is

[0031]

[Equation 2]

It becomes In equation (5), WT1, Ti
Since 1 and [Ti] are known, if the total titanium yield Ti2 is predicted from the primary titanium yield Ti1 using FIG. 5, the additional input titanium amount WT2 can be easily calculated.

In the seventh stage, titanium is additionally added to the molten steel as a secondary adjustment of the composition. As the additional input amount, the input amount calculated in the sixth stage is applied. The titanium to be charged is, for example, small-sized ferro titanium. Titanium is charged in the atmosphere while stirring the molten steel 9 with argon gas. Subsequent to the seventh step, in the eighth step, temperature measurement and sampling are simultaneously performed using the temperature measurement sampling device 7. Further, thereafter, the component analysis of the collected sample is performed. After the component analysis, the total titanium yield is calculated from the titanium analysis value in the ninth step. Following the ninth step, the function is updated in the tenth step. In the functions of the primary titanium yield and the total titanium yield, the oldest data and the latest data are replaced for each charge,
Updated with new functions. As a result, the prediction accuracy of the total titanium yield can be maintained at high accuracy even if the operating conditions change.

FIG. 6 shows the deviation between the analysis value of the final titanium concentration and the target value when the components were adjusted by applying the method of the present invention. L2 is a straight line where the analysis value and the target value match, L3 is a straight line where the analysis value is higher than the target value by 0.02%, and L4 is a straight line where the analysis value is lower than the target value by 0.02%. It can be seen from FIG. 6 that the deviation between the analysis value of the final titanium concentration and the target value is within 0.02%, so that the titanium concentration adjustment accuracy according to the method of the present invention is very good.

[0035]

As described above, according to the present invention, the titanium-containing steel containing chromium is agitated by blowing an inert gas, decarburized by oxygen blowing while preventing oxidation of chromium, and aluminum is added. Then, deoxidation is performed, and then titanium is added to manufacture. The deoxidation time of aluminum is determined based on the uniform mixing time determined by the stirring power and the volume of molten steel. In this way, after titanium is introduced after the deoxidation of molten steel and the reduction of slag by aluminum, the oxidation of titanium is suppressed. Oxidation suppression of titanium,
Since the yield of titanium is improved and the concentration of titanium is stabilized, the alloy cost can be significantly reduced. Further, since the present invention determines the deoxidizing time of aluminum based on the uniform mixing time having general versatility, it can be applied not only to specific equipment and specific operating conditions but also to various equipment and various operating conditions. You can

Further, according to the present invention, aluminum deoxidation is performed for a longer time than in the prior art, so that deoxidation of molten steel and reduction of slag are sufficiently performed. Therefore, the oxidation of titanium that is subsequently input is suppressed. Since the suppression of titanium oxidation brings about an improvement in titanium yield and a stabilization of titanium concentration, the alloy cost can be significantly reduced.

According to the present invention, titanium is added after deoxidizing aluminum as the primary adjustment of the components, and titanium is additionally added as the secondary adjustment. Since the input amount of titanium for secondary adjustment is determined through a logical procedure, the accuracy of titanium concentration adjustment is greatly improved. Therefore, products of stable quality can be continuously manufactured. Further, since the titanium concentration can be adjusted to a low value within the target component range, the generation of inclusions that cause streak defects is suppressed, and the surface quality of the product is improved.

Further, according to the present invention, since the functions of the primary titanium yield and the total titanium yield are obtained based on the moving average value of the immediately preceding operation, the total titanium yield is changed even if the operating conditions change. It is possible to maintain the prediction accuracy of the residue as high accuracy.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a simplified configuration of a vacuum ladle degassing apparatus capable of suitably carrying out the method of the present invention.

FIG. 2 is an explanatory view showing a melting process of titanium-containing stainless steel which is an embodiment of the present invention.

FIG. 3 is a diagram showing the relationship between the aluminum deoxidation time expressed as a multiple of the uniform mixing time and the primary titanium yield.

FIG. 4 is a diagram showing the relationship between the aluminum concentration of molten steel and the primary titanium yield in the method of the present invention.

FIG. 5 is a scatter diagram showing the relationship between the total titanium yield of 11% Cr-0.2% Ti steel and the primary titanium yield.

FIG. 6 is a diagram showing a deviation between an analysis value of a final titanium concentration and a target value when the components are adjusted by applying the method of the present invention.

FIG. 7 is a schematic diagram showing a simplified configuration of a vacuum ladle degassing device that can suitably perform the VOD method.

FIG. 8 is a diagram showing the relationship between the aluminum concentration of molten steel and the primary titanium yield in the prior art.

[Explanation of symbols]

1 80T vacuum ladle degasser 2 vessels 3 Vessel cover 4 vacuum exhaust means 5 suction tube 6 Oxygen-blown lance 7 Temperature measurement sampling device 8 alloy addition equipment 9 Molten steel 10 ladle 11 supply pipe 12 Porous plug 13 Internal space

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshiaki Miyamoto 4976 Nomuraminami-cho, Shinnanyo-shi, Yamaguchi Nisshin Steel Co., Ltd. Shunan Steel Works (56) Reference JP-A-5-337616 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C21C 7/00 C21C 7/06 C21C 7/072

Claims (4)

(57) [Claims] 1. A method for producing a titanium-containing steel in which aluminum and titanium are charged into a molten steel containing chromium, wherein a predetermined amount of oxygen is blown into the chromium while the inert gas such as argon is blown from the bottom of the container to stir the chromium. When oxygen is blown to decarburize while preventing the oxidation of aluminum, and aluminum is added while stirring is continued even after the oxygen blow is stopped, and the stirring power is ε and the volume of molten steel is V1, the equation log (tm) = 2.5-0.45log (εV1 ^-2/3) after holding only 12 times or less the time 7 times the uniform mixing time tm by deoxidation satisfying, and wherein placing the titanium Method for producing titanium-containing steel. 2. The method for producing titanium-containing steel according to claim 1, wherein the holding time while stirring is 5 minutes or more and 10 minutes or less. 3. A method for producing a titanium-containing steel in which aluminum and titanium are charged into molten steel, in which aluminum is charged and an inert gas such as argon is blown from the bottom of the container and stirred for a predetermined time. After performing deoxidation by adding titanium, the components are first adjusted by adding titanium, the yield of the added titanium is determined as the primary titanium yield, and additional titanium is added to the molten steel as the second adjustment. When
The total titanium yield, which is the yield of titanium input as the primary adjustment and the secondary adjustment, is predicted by using a preset function of the primary titanium yield and the total titanium yield, and is predicted. A method for producing titanium-containing steel, which comprises determining the amount of titanium for secondary adjustment necessary to obtain a target concentration of titanium based on the total titanium yield. 4. The method for producing titanium-containing steel according to claim 3, wherein the function of the primary titanium yield and the total titanium yield is obtained based on the moving average value of the immediately preceding operation. .